I figure there's an undiscovered trope waiting to be discovered here. Here's the two examples I can remember of characters violating the laws of physics to break up with their girlfriends.

Going back in time to prevent yourself from hooking up -- Superman II: The Donner Cut

Hooking her up with a clone of yourself -- Doctor Who

EDIT: Feel free to ignore my instructions and just go with break-ups that can only happen in sci-fi/fantasy.

Phoenix from the future telling Cyclops to make out with Emma Frost over her grave in X-Men.

Turning Evil -- Buffy & Angel.

Buffy, you make me so happy I have to kill people and destroy the world.

Not really violating the laws of physics, but a Cylon broke up with another Cylon because he didn't know he was a Cylon, and thought she was a Cylon, and even though she didn't KNOW she was a Cylon, she suspected she was a Cylon, and had no clue that he actually was a Cylon.

AIRLOCK BOOMER

I am now totally down with this just being Sci-Fi break-ups without any physical laws being broken.

What Steven is trying to say is that no matter how hard we try, we will never find anything as dumb as that Suoerman bit.

Don't mind me. I'm trying to pronounce "Suoerman".

Marty McFly realigned the space-time continuum just because he wasn't interested in the girl that liked him.

Granted, she was his mother, but still....

Of course, the breakup in Eternal Sunshine of the Spotless Mind. I don't want to just break up with you, I want to eradicate all my memories of you. Done.

And more recently by the same director:: a computer breaking up with you because it has fallen in love with 800 other people and is planning to integrate itself (along with many other OS entities) with vast cosmic forces. But don't worry, it's not "you" it's "me".

I also see the scene in 2001 when Hal is disconnected as a sort of cosmic breakup moment.

Or, later when Dave Bowman "breaks up" with his species, evolutionary speaking.

Yes. Dave breaks up with a lot of people in that movie. He's sort of a cosmic whore.